Influence of Co-doping on optical properties and traps localization of ZnO films obtained by spray pyrolysis

We report a systematic investigation on the structural and optical properties of Co-doped ZnO and Co3O4 thin films grown by spray pyrolysis using acetates as precursors in low molarity solutions. XRD and optical transmittance measurements do not show secondary phases. Optical measurements exhibit the Co2+ signatures related to tetrahedral coordination in absorption and emission. Temperature-dependent PL shows the influence of traps up to 200 K when they are shielded by thermal energy. The qualitative potential fluctuations model allows the evaluation of traps depth of as tenths of meV and the influence of Co-doping in the neighborhood of optically active Co2+.